This post has been corrected.

President Trump’s campaign was seconds old when he started criticizing America’s policy on immigration. That he described immigrants from Mexico as criminals in his announcement speech earned him an enormous amount of attention — attention that was largely beneficial to his candidacy. That those comments came so early in his speech is probably just as notable, showing the priority he placed on the issue. The first subject he raised in that speech, though, as an aside dissing his opponents? The fight against the Islamic State.

A lot of attention has been paid to Trump’s appeal to the economic insecurity faced by his white, working-class supporters. Yet exit polling reinforces how important the issues of terrorism and immigration were to his base, as well. In nearly every swing state, voters voting on the economy preferred Democrat Hillary Clinton. But Trump won, thanks to strong support from voters worried about terrorism and immigration.

Earlier this month, Pew Research released the results of an international survey that touches on this topic tangentially. What does it take, Pew asked, for you to consider someone to share your national identity? Responses varied by geography, with people in the United States less likely to say that shared cultural traditions were essential to being truly “American” — but more likely to say that Christianity was.

It’s hard to measure something like adherence to cultural norms among a large population. But we can measure — and researchers have measured — how frequently new immigrants speak English or practice Christianity.

The most recent data on language comes from the Census Bureau (via Pew, once again). About half of immigrants spoke English moderately well in 2013, down a bit from 1980.

The geography of where immigrants speak English well varies, with immigrants in states like Oklahoma, Texas and California less likely to speak the language well. That’s because English skills were lower, in the Census Bureau’s estimation, among immigrants from Mexico and Latin America.

As for religion, 2016 was an unusual year. For the first time, Pew estimated (based on countries of origin) that more Muslims came to the United States as refugees than Christians.

The most recent data on immigrants overall is a bit older. While most new immigrants were Christian as of 2012, the share of that population which is Muslim doubled since 1992.

Those two groups — immigrants from Central America and Muslim immigrants — overlap with the rhetoric of the Trump campaign that appealed to so many voters. The data from Pew’s study on assimilation makes that overlap clear.

Trump’s core of support during the campaign came from whites without college educations, Republicans and evangelical voters (and the overlap of those three). In Pew’s research, those are also groups that were more likely to consider it very important for someone to speak English or be Christian to be seen as American.

By education:

By political party:

Views among evangelicals:

In other words, Trump’s base of support overlaps with demographic groups that Pew found were more likely to see immigrants from Mexico and Latin America or Muslim countries as un-American.

We’re running a thin thread through a number of different things here, correlating data and wondering about causation. But Pew’s findings fit neatly with why Trump’s twin messages of curtailed Latin American and an outright ban on Muslim migration weren’t dealbreakers to his core supporters.

A call to make America great again depends entirely on whom you consider to be American.

Correction: Incorrect data about the religion of immigrants has been updated.